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ISA 75.17-1989
Control Valve Aerodynamic Noise Prediction (Downloadable)
This standard establishes a method to predict the noise generated in a control valve of standard design by the flow of compressible fluid and the resulting noise outside of the pipe and downstream of the valve. The transmission loss (TL) equations are based on a rigorous analysis of the interaction between the sound waves that exist in the pipe and the many coincidence frequencies in the pipe wall. Commercial pipe specifications allow a relatively wide tolerance in pipe wall thickness. This limits the value of the very complicated mathematical methods required for a rigorous analysis; calculations prove that a simplified expression is justified. The equations in this standard make use of the valve sizing factors defined in ANSI/ISA-75.01.01-2007 and ANSI/ISA-75.02.01-2008. This method was developed from the fundamental principles of acoustics, fluid mechanics, and mechanics. The standard addresses only aerodynamic noise and does not consider noise generated by mechanical vibrations, unstable flow patterns, and other unpredictable behavior.
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The International Society of Automation [isa]
